COVID-19 vaccines protect against hospitalisation and death longer than they protect against infections
Embargoed until:
Publicly released:
2024-09-06 00:01
COVID-19 vaccination and infection data from over 5 million people in Aotearoa shows that vaccines and boosters were most effective within the first few months after injection, but even after protection against infection declined they continued to protect against hospitalisation and death. They found the decrease in vaccine effectiveness over time was similar to other international studies; for example, in the first to the sixth month after the second booster vaccine its efficacy dropped from almost 82% to 49% in protection against hospitalisation, but from over 57% to just under 10% protection against infection. The study authors recommend future studies to understand how effectiveness changes beyond six months, and differences by vaccine type and COVID-19 variant.
Journal/conference: New Zealand Medical Journal
Organisation/s: Victoria University of Wellington, University of Auckland, ESR (Institute of Environmental Science and Research Ltd), Massey University
Funder: This work was supported by the Ministry of Health, Aotearoa New Zealand (reference: PROP–053). The sponsors of the study had no role in the design, data collection, data analysis, data interpretation or the writing of this report. There was no input to the methodology and results by any commercial entity.
CR Simpson, AA Sporle, J Shephard, A Su’a-Tavila, BP Nguyen and N French report support for the present manuscript from the Ministry of Health (NZ).
Media release
From: Pasifika Medical Association Group
Our study analysed data from over 5 million people to understand the effectiveness of COVID-19 vaccines over time. The COVID-19 vaccine was found to have sustained protection against death from COVID-19 over the study period and was most effective at preventing hospitalisation and infection in the initial months after each dose. In later months, the second booster vaccine dose, which initially reduced hospitalisations by 81.8%, decreased to 49.0% by month 6. Similarly, protection against infection dropped from 57.4% to 9.9% during the same period. This decline in vaccine effectiveness was observed across all groups in the study.
